ORS § 238.655
In order to determine any facts necessary to the administration of the retirement system, the board may conduct hearings, subpoena and examine witnesses and require any person having custody thereof to bring before the board any book, record, document, certificate, writing, article or thing necessary to a determination of facts. The chairperson or member of the board acting in such capacity shall have authority to administer oaths. The procedure in such hearings shall be informal. Fees shall not be paid to witnesses who are public officers or employees, whether or not their employer is participating in the system. No public employer shall make deduction from the compensation of public officers or employees because of absence from their respective positions in order to be examined as witnesses before the board. The fees of other witnesses and mileage of any witness shall be as allowed by law to witnesses in ORS 44.415(2). Fees and mileage and all other necessary disbursements in connection with a hearing shall be paid by the public employer whose failure or refusal to supply any facts requested of it by the board made necessary such hearing.
ORS 238.655